There is an ever increasing number of therapeutic fluids being developed for delivery by a flexible receptacle. Many of these therapeutic fluids are sensitive as they degrade or react with gases such as oxygen and carbon dioxide. These therapeutic fluids must be protected from contact by such gases to maintain the efficacy of the therapeutic fluid.
For example, hemoglobin solutions are known to lose their ability to function as blood substitutes during storage. A hemoglobin solution loses its ability to function as a blood substitute because of spontaneous transformation of oxyhemoglobin in the solution to methemoglobin, a physiologically inactive form of hemoglobin which does not function as a blood substitute by releasing oxygen into a patient's bloodstream. To improve shelf life, the blood substitutes industry delays loss of function by refrigerating or freezing the solutions, or controlling the oxygenation state of the hemoglobin within the solution.
Therapeutic hemoglobin solutions are typically oxygenated, stored frozen in conventional oxygen-permeable, 200 ml plastic solution bags, and thawed to room temperature hours before use.
WO 99/15289 describes a multiple layer structure for fabricating medical products. The layer structure has a core layer of an ethylene vinyl alcohol copolymer, a solution contact layer of a polyolefin positioned on a first side of the core layer, an outer layer positioned on a second side of the core layer opposite the solution contact layer, the outer layer being selected from the group consisting of polyamides, polyesters and polyolefins, and a tie layer on each side of the core layer. The tie layer is 0.2-1.2 mils in thickness, and is the only layer of the structure which may be composed of ethylene vinyl acetate.
U.S. Pat. No. 6,271,351 describes a method of storing deoxyhemoglobin in a container which is said to exhibit low oxygen permeability. The container is composed of a layered structure including ethylene vinyl alcohol, but does not include ethylene vinyl acetate.
There is a need for containers having minimal oxygen permeability which would enable deoxygenated hemoglobin solutions to be stored for weeks or months at room temperature and then used as a blood substitute.
Receptacles used for the shipping, storing, and delivery of liquids, such as medical or therapeutic fluids, are often fabricated from single-ply or multiple-ply polymeric materials. Two sheets of these materials are placed in overlapping relationship and the overlapping sheets are bonded at their outer peripheries to define a chamber or pouch for containing liquids. It is also possible to extrude these materials as a tube and to seal longitudinally spaced portions of the tube to define chambers between two adjacent seals. Typically, the materials are joined along their inner surfaces using bonding techniques such as heat sealing, radio-frequency sealing, thermal transfer welding, adhesive sealing, solvent bonding, sonic sealing, and laser welding.
It is also common to provide such receptacles with access ports to provide access to the interior of the receptacle. Access ports typically take the form of one or more end ports (transfer tubes) inserted between the sidewalls of the receptacle or panel ports attached to a sidewall of the receptacle. The end ports typically have a fluid passageway with a closure wall positioned inside the passageway to form a fluid tight seal of the receptacle. The closure, typically in the form of a membrane, must be punctured by an access needle or “spike” to allow for delivery of the contents of the receptacle.
Conventional flexible solution receptacles employing end port designs typically use flexible PVC or soft polyolefins such as LDPE to construct the port tubes. Such materials have sufficient elasticity to grip the outside of an access spike to retain the spike during fluid delivery. The inner diameter of the end ports are dimensioned to be smaller than the outer diameter of the access device. Due to the ductility of PVC or LDPE, the port tube can expand about the outside of the access spike to form an interference fit therewith. However, such receptacle and port closure systems are readily permeated by oxygen and other gases such as carbon dioxide. If such receptacles are to be utilized to house a gas sensitive liquid, such packages must utilize a gas barrier overwrap material.
To provide a stand-alone gas barrier primary receptacle, all components of the receptacle system should be fabricated using barrier material. For medical applications where such receptacles are typically disposed of by incineration, it is desirable to construct the receptacle system components from non-halogen containing polymers. Halogen containing compounds have the potential for creating inorganic acids upon incineration. Further, for medical applications, it is also desirable to construct the receptacle system components from polymers having a low quantity of low molecular weight additives, such as plasticizers, as such low molecular weight components can potentially leach out into the fluids contained or transported therein.
It is well known that certain materials provide a high resistance to the ingress of oxygen or other gases. For example, ethylene vinyl alcohol (EVOH) provides a high barrier to the ingress of oxygen. However, EVOH provides a significant design challenge for use in flexible receptacle systems as EVOH is also know to be a very rigid material. A port tube containing a significant quantity of EVOH will have insufficient elasticity to expand around an access device. Thus, such an EVOH containing port tube cannot be dimensioned to be smaller in diameter than an access device.
Due to the variation in the outer diameter dimensions of access devices commercially, it is also difficult to design a single port tube to have an appropriate diameter to form an interference fit with all access devices commercially available. The spike holder or needle holder has sufficient elastomeric properties to form around an access device and form a grasping hold of the access device. The present invention is provided to solve these and other problems.